The crystallisation of the latest technology of valves:triple offset butterfly valve

Oct 16, 2023 | News

The most traditional and common classification of butterfly valves is the concentric butterfly valve, which is structurally characterized by the stem axis, butterfly plate centre and body centre in the same position. The structure of concentric butterfly valve is simple and easy to manufacture. Butterfly plate and valve seat are always in the state of extrusion, scraping, large resistance distance, fast wear. In order to overcome the extrusion, scraping, to ensure the sealing performance, now appear on the market offset butterfly valve.

Butterfly valve whose stem axis deviates from the centre of the disc and the centre of the body at the same time, and whose sealing vice is inclined vertebrae, is called offset butterfly valve. This technology overcomes the leakage problem to a great extent.

offset butterfly valves can also be subdivided into single offset butterfly valves, double offset butterfly valves and triple offset butterfly valves according to different structural forms.

In this article TWT,China will detail these three offsetities for buyers.

triple offset butterfly valve

Single offset butterfly valve

The structural characteristics of single offset butterfly valve is that the stem axis deviates from the centre of the butterfly plate, so that the upper and lower ends of the butterfly plate no longer become the axis of rotation, dispersion, reducing the excessive extrusion of the upper and lower ends of the butterfly plate and the valve seat, and solving the problem of concentric butterfly valves of the butterfly plate and the seat of the extrusion problem.

However, because of the single offset structure in the valve throughout the switching process of the butterfly plate and seat scraping phenomenon has not disappeared, in the scope of application and concentric butterfly valves are similar, so the use of not much.

Double offset butterfly valve


The double offset butterfly valve is an improvement on the single offset butterfly valve, which is also the most widely used. Its structural characteristics consist of the fact that the axis of the valve stem deviates from both the centre of the butterfly plate and the centre of the body. The effect of the double offsetity means that the valve is opened after the butterfly plate can be quickly separated from the valve seat, greatly eliminating the butterfly plate and seat from unnecessary excessive pressure, the phenomenon of scraping, reduces the opening distance, reduces wear and improves the service life of the valve seat.

The risk is greatly reduced, but it also means that the double offset butterfly valve can also be used with a metal seat, improving the butterfly valve in the field of high temperature applications.

Application of double offset butterfly valve

Double offset butterfly valves are also called high performance butterfly valves, mainly used in water plants, power plants, steel mills, chemical industry, water source spring projects, environmental facilities construction and other system drainage, especially suitable for waterway pipelines, as regulating device and shut-off device.

Drawbacks of double offset butterfly valve

Because the sealing principle of double offset butterfly valve is positional sealing structure, i.e. the sealing surface of the butterfly plate and the valve seat is in line contact, and the sealing effect is produced by the elastic deformation caused by the squeezing of the butterfly plate on the valve seat, so it has high requirements for the closing position (especially for the metal valve seat), and low pressure-bearing capacity.

That’s why our major theme,triple offset butterfly valve came out.

Triple offset butterfly valve

The biggest feature of the third offset is to fundamentally change the sealing structure, no longer positional sealing, but torque sealing, that is, not relying on the elastic deformation of the valve seat, but completely relying on the seat of the contact surface pressure to achieve the sealing effect.The stem axis of triple offset butterfly valve deviates from the disc centre and the body centre at the same time, and the valve seat rotary axis is at an angle with the valve channel axis.

This initiative solves the problem of zero leakage of metal valve seat, and because the contact surface pressure is proportional to the medium pressure, high pressure and high temperature resistance is also solved.

What are the three offsets?

  1. The first offsetis the valve shaft is located behind the valve plate shaft, so that the seal can be completely close around the contact with the entire valve seat.
  2. The second offsetity is that the centre line of the valve shaft deviates from the centre line of the pipeline and the valve to avoid the interference of the valve opening and closing.
  3. The third offsetity is that the cone axis of the valve seat is off the centre line of the valve axis, so as to eliminate friction in the process of closing and opening, and to achieve uniform compression sealing effect around the entire valve seat.

Application and advantages of triple offset butterfly valve

Triple offset disc valves are available in pressure ratings up to 2500 pounds, temperatures as low as -196°C, and as high as 700°C, with zero leakage and a control ratio of 100:1. That is to say, in a variety of harsh, critical process control pipelines, whether it is a switching valve or control valve, as long as the selection of the right type, now can be assured that the use of disc valves, and low cost.